Generally, an electronic apparatus is provided with a wiring board, connector units (for external connection) arranged at the periphery of the wiring board, connection members for electrically connecting the wiring board with the connector units, and a case unit at which the wiring board and the connector units are mounted.
Recently, it is preferable for the wiring board to be miniaturized, that is, a connection space for the connection between the wiring board and the connector unit to be reduced, in order to small-size (high-density package) the electronic apparatus.
In the conventional electronic apparatus, the wiring board and the connector unit are connected with each other through the connection member such as a bonding wire, after the wiring board and the connector unit are mounted at the case unit.
However, if the connection space for the connection between the wiring board and the connector units is narrowed, a connection device and a connection jig will interfere with components adjacent thereto when performing the connection operation. Therefore, it is difficult to small-size and high-density package the electronic apparatus.
The interference in the connection via the connection member will be described with reference to FIGS. 7 and 8.
As shown in FIG. 7, an electronic apparatus as a first comparison example is provided with a case unit 10 having an opening portion 11, whose bottom surface functions as a mounting surface 12. A wiring board 20 and connector units 30 for an external connection are mounted at the mounting surface 12. A surface 11a of the edge of the opening portion 11 is a mounting surface, through which the electronic apparatus is attached to an attachment member (not shown).
Electronic components 24, 25, and pads 23 connected with a bonding wire 40 (as connection member) are mounted at the wiring board 20. The connector units 30 are arranged at the periphery of the wiring board 20.
The connector unit 30 of the side of an external connection surface 32 is connected with an external wiring member such as wire harness. The connector unit 30 made of resin is provided with a terminal 31 which is connected with the bonding wire 40 and constructed by insert-molding.
In the connector unit 30, a surface opposite to the external connection surface 32 functions as a terminal installation surface 33 on which the terminal 31 is provided. The terminal 31 and the pad 23 of the wiring board 20 are electrically connected with each other via the bonding wire 40.
In this case, as shown in FIG. 7, both the pad 23 of the wiring board 20 and the terminal 31 of the connector unit 30 are arranged at an opposite side of the wiring board 20 to the mounting surface 12 of the case unit 10. That is, the pad 23 and the terminal 31 do not face the mounting surface 12 of the case unit 10. In this state, the wiring board 20 and the connector units 30 are mounted at the mounting surface 12 of the case unit 10, and thereafter the connection via the bonding wire 40, that is, the wire bonding is performed.
However, in this case, a bonder 300 of a wire bonding device interferes with a sidewall of the case unit 10, so that the wire bonding becomes difficult.
In the case with reference to FIG. 7, after performing the fist bonding at the pad 23 of the wiring board 20, the second bonding is performed at the terminal 31 of the connector unit 30. Thereafter, when the bonder 300 is made step back in order to cut the wire 40, the bonder 300 will interfere with the sidewall of the case unit 10.
In order to prevent the interference, it is necessary to enlarge a distance L1 between the terminal 31 and the case unit 10 to widen a connection space. As a result, the electronic apparatus becomes large. Therefore, it is difficult to small-size the electronic apparatus in this case.
On the other hand, even when the first bonding is performed at the side of the terminal 31, the interference of the bonder 300 similarly to what is described above will occur in the case where the distance L1 between the terminal 31 and the case unit 10 is small.
Referring to FIG. 8, an electronic apparatus as a second comparison example has a case unit 10 with a substantial flat-plate shape. A first surface of the case unit 10 is used as a mounting surface 12. A wiring board 20 and connector units 30 are mounted at the mounting surface 12. The case unit 10 has a second surface (at opposite side to mounting surface 12), at which the electronic apparatus is attached to an attachment member (not shown).
Similarly to the case of FIG. 7, electronic components 24, 25 and pads 23 are arranged on the wiring board 20. Moreover, the connector units 30 are arranged at the periphery of the wiring board 20.
Referring to FIG. 8, both an external connection surface 32 and a terminal installation surface 33 of the connector unit 30 are positioned at the side (of connector unit 30) opposite to the mounting surface 12 of the case unit 10. That is, the external connection surface 32 and the terminal installation surface 33 do not face the mounting surface 12. Therefore, a part (in vicinity of terminal 31) of the connector unit 30 of the side of the external connection surface 32 will interfere with the bonder 300. That is, an interference between the bonder 300 of the wire bonding device and the connector unit 30 is caused, so that the wire bonding becomes difficult.
In this case, after the first bonding is performed at the terminal 31 of the connector unit 30, the second bonding is performed at the pad 23 of the wiring board 20. In performing the first bonding, the bonder 300 interferes with the connector unit 30.
In order to prevent the interference, it is necessary to enlarge a distance L2 between the terminal 31 and the external connection surface 32 of the connector unit 30 to widen a connection space. Thus, the size of the electronic apparatus becomes large, so that the miniaturization thereof becomes difficult. The interference occurs similarly in the case where the first bonding is performed at the side of the pad 23 in FIG. 8.
As described above, in the electronic apparatuses shown in FIG. 7 and FIG. 8, the interference of the bonding device is caused in the wire bonding. The electronic apparatus will become large, if the distance between the bonding device and the interfering element such as the case unit and the connector unit is enlarged in order to ensure a sufficient connection space.
The above-described problem is not only caused in the case where the connection between the wiring board and the connector unit is established via the wire bonding, but also caused in the case where a flexible printed circuit board is used as the connection member. In this case, a pressing/heating jig for the connection interferes with the above-described interfering elements.
Therefore, according to the conventional electronic apparatus (referring to first and second comparison examples), there exits a trade-off relationship between realization of a sufficient connection space and realization of a miniaturization of the electronic apparatus, so that it is difficult to satisfy these requirements simultaneously.